The distribution and abundance of phytoseiid mites (Acari: Phytoseiidae) on citrus in southern Africa and their possible value as predators of citrus thrips (Thysanoptera: Thripidae)

Abstract

Grout, T.G.. 1994. The distribution and abundance of phytoseiid mites (Acari: Phyloseiidae) on citrus in southern Africa and their possible value as predators of citrus thrips (Thysanoptera: Thripidae). Exp. Appl. Acarol., 18:61--71.On citrus in Zimbabwe, Swaziland and South Africa, predacious mites of the subfamily Amblyseiinae are more common and found in greatc, numbers than phytoseiids of the subfamily Phytoseiinae. The author's survey and other collection data indicated that within the Amblyseiinae the genus Euseius Wainstein is the most widely distributed. Seven Euseius spp. have been recorded on citrus in the above countries but not more than one species has been found at any particular site and time. E. cirri (Van der Merwe and Ryke) has the broadest geographical distribution and is capable of suppressing population levels of the citrus thrips Scirtothrips atwantii Faure. However, it is not as effective a biocontrol agent as E. addoensis Wan der Merwe and Ryke) which occurs in higher numbers further south. An orchard comparison of the non-target effects of thripicides showed that E. cirri was more susceptible to sabadilla alkaloids (0.0024% AI) plus sugm-(0.96%) than to tartar emetic (0.398% A]) plus sugar (0.4%). The author's survey provides the first records of E. orygmus ~Ueckermann and Loots) and E. tutsi (Pritchard and Baker) on citrus in Zimbabwe. Typhlodromalus Muma spp. were not widely distributed but where they did occur they were often abundant and sometimes coexisted with Euseiu~" spp. Circumstantial evidence indicated that Typhlodmmalus spp+ may be effective thrips predators. The combination of Euseius and T.,;phlodromalus spp. may provide more effective biological control of citrus thrips than either species alone. Ambl),dromella Muma spp. were the only representatives of the subfamily Phytoseiinae currently found on citrus and they occurred only in the Transwtal and Natal provinces of South Africa. The possibility that Amblydromella spp. compete with Amblyseiinae is discussed.

Intraguild interactions between Euseius stipulatus and the candidate biocontrol agents of Tetranychus urticae in Spanish clementine orchards: Phytoseiulus persimilis and Neoseiulus californicus

“…Euseius species are among the most common phytoseiid species in citrus-growing regions worldwide (Grout 1994;McMurtry 1985). In particular, E. stipulatus is the most abundant and widespread phytoseiid species on citrus in the Mediterranean area (McMurtry 1977) indicating good adaptation to citrus agro-ecosystems (McMurtry 1989).…”

Seasonal fluctuation in population density of phytoseiid mites and the yellow tea thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) on grape, and predation of the thrips by Euseius sojaensis (Ehara) (Acari: Phytoseiidae)

“…Many species of plant-inhabiting phytoseiid mites, which feed on thrips, have been recorded in the world (Sabelis and Van Rijn, 1997). In South Africa, Euseius addoensis (Van der Merwe and Ryke) significantly reduces the population of Scirtothrips aurantii Faure on orange groves (Grout and Richards, 1992) and Amblyseius citri Van der Merwe and Ryke [Euseius citri (Van der Merwe and Ryke)], although not as effective as E. addoensis, can control S. aurantii on citrus (Grout, 1994). In California, the predatory role of Euseius hibisci (Chant) on Scirtothrips citri (Moulton) on citrus was evaluated (Tanigoshi et al, 1985).…”

Survey of predacious mites on citrus in South Africa. Specific diversity, geographic distribution and the abundance of predacious mites

“…Four sites per orchard were randomly selected and trees in every site were beaten with a stick over a rigid plastic board for almost a constant period of time (30 sec) (GROUT, 1994). Predators accumulated on the board were removed with a fine hair brush and preserved in 70% alcohol.…”

“…Therefore, under hot-dry conditions and/or application of insecticide predacious mites would have been destroyed or eleminated and in their absence red spider mite populations are likely to increase very rapidly. In a previous study, GROUT (1994), provided information on the predacious mites in Southern Africa and their association with thrips …”